Disclinations in nanocrystalline materials: Manifestation of the relay mechanism of plastic deformation
Disclinations in nanocrystalline materials: Manifestation of the relay mechanism of plastic deformation
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DOI：
10.1016/j.msea.2008.05.053
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发表时间：
2009-03
期刊：
影响因子：
6.4
通讯作者：
A. Romanov;A. Kolesnikova;I. Ovid’ko;E. Aifantis
中科院分区：
文献类型：
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作者：
A. Romanov;A. Kolesnikova;I. Ovid’ko;E. Aifantis
讨论了向错在纳米晶材料变形行为和结构形成中的作用。简要概述了向错缺陷的性质。然后提出了一些基于向错的模型来解释NCM的力学性能。建立了NCM中塑性剪切扩展的位错-向错传递模型。该模型基于塑性变形的平移和旋转变形模式之间的切换。认为NCM中的平移模式是由于晶界位错滑移，旋转模式是由于楔结向错的形成，而楔结向错是由晶界位错运动或晶界扩散的协同过程产生的。在接力位错-向错机制作用的情况下，证明了不同晶粒长径比下变形应力对晶粒尺寸的依赖关系。结果表明，从一种模式到另一种模式的过渡可能有助于在NCM中观察到的反Hall-Petch关系低于临界晶粒尺寸。
The role of disclinations in deformation behavior and structure formation of nanocrystalline materials (NCMs) is discussed. A short overview of the properties of disclination defects is given. Then a number of disclination-based models is advanced for the explanation of NCM mechanical properties. The relay dislocation–disclination model of plastic shear propagation in NCM is developed in detail. This model is based on the switching between translation and rotation deformation modes of plastic deformation. It is argued that the translation mode in NCM is due to the grain boundary dislocation sliding and the rotation mode is due to the formation of wedge junction disclinations which emerge by co-operation processes of intergrain dislocation motion or co-operative grain boundary diffusion. The dependence of deforming stress on the grain size for various grain aspect ratios is demonstrated in the case of relay dislocation–disclination mechanism operation. It is shown that the transition from one mode to another may contribute to the inverse Hall–Petch relationship observed in NCM below a critical grain size.